Long-term high-risk human papillomavirus incidence and clearance in population based cervical screening, as retrieved from a second screening round in the POBASCAM study
01 / 2005 - unknown
Based on high-risk human papillomavirus (hrHPV) infection being the major causative factor of cervical cancer, substantial evidence has been obtained that cervical screening might become more efficient if testing for hrHPV is added to cervical cytology. Most evidence obtained so far from population-based research is based on follow-up studies with either relatively small numbers of women, or relatively short follow-up periods. However, it is clear that additional hrHPV testing can only lead to more cost-effective screening strategies if the screening interval can be prolonged for double negative women, i.e., women with normal cytology and a negative hrHPV test result. From previous research and preliminary simulation studies we anticipate that the screening interval in The Netherlands might be prolonged from 5 to 8 or even 10 years for double negative women. Based on the data collected so far the potential advantages of adding hrHPV testing to cytology for screening can be summarized as follows: 1. Improvement of the negative predictive value for lesions In this study we aim to collect during a 2-year period HPV samples of the next screening round of women who participate in the POBASCAM trial for hrHPV and viral load testing. The main question that will be addressed is: 1) How many incident CIN 2/3 (cq. CIN 3) cases are found after 5 years in hrHPV negative women with normal cytology and BMD at baseline and is hrHPV acquisition after 5 years predictive of these incident CIN2/3 (cq. CIN 3) lesions? Population based cervical screening by cytology has resulted in a decrease of the incidence of and mortality from squamous cervical cancer in The Netherlands, but has failed to reduce the long term incidence of cervical adenocarcinomas. A recent study from our department and data from the National Cancer Registry and other studies show that adenocarcinomas are missed in cervical screening by cytology  The POBASCAM study is being conducted in the area of Amstelland-De Meerlanden and Midden and Zuid-Kennemerland. In this area, all parties involved in screening, including over 250 general practioners and 4 pathology laboratories, are used to hrHPV testing in addition to cervical cytology, and the infrastructure of hrHPV testing in primary screening is presently still fully operational. We have conducted the intake of the POBASCAM study between January 1999 and February 2002 and all 44,102 women included, 30?60 years of age, have been hrHPV tested at baseline. Since we need data about long-term behavior of hrHPV infections, a subset of women who have been hrHPV tested in cervical screening will be retested at a second screening round after 5 years. Starting in 2004, we will collect the smears of the next screening round during a 2-year period in universal collection medium (UCM). Women older than 56 years of age at the time of enrollment are not invited for another screening round, and will not have long-term follow-up hrHPV tests. During the first two years of the POBASCAM study, about 16,000 women from 30-55 years of age have been enrolled. With 80% attendance of the next screening round, we expect to collect about 12,500 HPV long-term follow-up samples. Given the POBASCAM baseline data , we expect that these samples represent the following categories of women on the basis of cytology and hrHPV test results at initial screening in 1999-2000: 11,700 Pap 1-hrHPV negative; 460 Pap1-hrHPV positive; 220 BMD-hrHPV negative; and 120 BMD-hrHPV positive.